R spondin

The organoid culture was performed in accordance to the protocol described previously [21 ]. In brief, organoids were generated from isolated crypts of the colon of colitis mice (C57/BL6 mice and Lrrc19^−/− mice) and then embedded into Matrigel (Corning, Corning, New York, USA). After that, organoids were kept in Organoid Growth Medium (STEMCELL Technologies) in the presence of R-Spondin, Noggin, and EGF (Proteintech). To investigate the effect of DVF on organoids, organoids were co-cultured with 1 μg DVF or PBS on 6-well plates. After 5 days of co-culture, organoid morphologies were recorded and then harvested for further experiments.

Intestinal organoids were generated from the small intestinal crypts isolated from two-month-old mice using the method previously described^{70 (link)}. Briefly, mouse intestine was dissected and intestinal epithelium was separated by ice-cold 5 mM EDTA-PBS. Following vigorously shaking, intestinal crypts were collected by centrifuge at 4 degree. The intestinal crypts were then resuspended and cultured in the Geltrex® Matrix (Thermo Fisher) in the presence of R-Spondin, Noggin and EGF (Proteintech), and split 4 times before MGH-CP1 treatment. The complete medium and the inhibitor were changed every 2 days.